The present disclosure relates to chemical compositions, and particularly to compositions for developable bottom antireflective coating (DBARC) material, structures, methods of making and using the same.
High reflectivity from the substrate has become increasingly detrimental to the lithographic performance of photoresists for high numerical aperture (NA) and short ultraviolet (UV) wavelength (such as 248 nm, 193 nm, and shorter wavelengths) exposures. The problem of the negative impact of high reflectivity on lithographic performance is more pronounced in implant levels owing to the existence of surface topography generated after gate patterning and/or use of various reflective substrates (such as substrates including silicon, silicon nitride and silicon oxide) for advanced semiconductor devices.
Use of a top antireflective coatings (TARC) layer to improve lithographic images is known in the art. The reflectivity control provided by a TARC layer is in general not as good as reflectivity control provided using a bottom antireflective coating (BARC) layer. Using a BARC layer, however, requires an etch step for removing the BARC layer. This etch process could damage the underlying substrate, and thus, use of a BARC layer is not desirable for many applications including implant levels.
Two types of photoresists are known in the art. A positive photoresist is a type of photoresist in which the portion of the photoresist exposed to light becomes soluble to the photoresist developer. The portion of the photoresist that is unexposed remains insoluble to the photoresist developer. A negative resist is a type of photoresist in which the portion of the photoresist exposed to light becomes insoluble to the photoresist developer. The unexposed portion of the photoresist is dissolved by the photoresist developer.
A DBARC layer has been proposed to alleviate the reflectivity control issues for positive photoresists. DBARC materials known in the art include materials that are compatible only with positive photoresists. DBARC systems for positive resists are disclosed, for example, in U.S. Pat. No. 6,844,131 to Oberlander et al. and U.S. Patent Application Publication Nos. 20070243484 to Chen et al. and 20100196825 to Huang et al. The DBARC material for positive photoresists becomes soluble to photoresist developer upon irradiation with light in the same manner as the positive photoresists.
However, many implant levels in semiconductor manufacturing employ negative photoresists because negative photoresists provide superior clearing of resist images over topography, and less resist shrinkage during ion implantation compared with positive photoresists. Therefore, there is a need for a DBARC system suitable for use with a negative photoresist.